During the first half of the 11th century the Přemyslid Duke Bretislaus I and his sons fortified the line along the Dyje River against possible attacks from Austria.
The old Moravian castle at Hradiště across the Granice Valley was not up to the required military standards. The Přemyslid Dukes decided to build a new fortress on a large protruding rock opposite Hradiště, which gave excellent views to the river valley and its surroundings.
The building of the first wooden castle would have been completed around 1080 and from this time Znojmo Castle enjoyed important roles in diplomatic and wartime contacts between the Bohemian Dukes (later kings) and the Austrian represents of the Holy Roman Empire.
In 1100 the famous wedding ceremony of Borivoj II, Duke of Bohemia, was held at Znojmo Castle.
Forty years later, when Znojmo belonged to Duke Conrad of Znojmo, the castle was besieged and finally burnt down by the troops of the Bohemian Duke Vladislaus II.
At the end of the 12th Century the castle was rebuilt from stone and divided in two parts by a deep moat. The rear part of castle contained the palace and palace chapel, and the front part contained military barracks and the St. Catherine’s Rotunda. The entrance to the castle was guarded by a mighty, tall, octagonal tower – the so-called “Robbers Tower”, which unfortunately collapsed due neglect at the end of the 19th century (in fact it collapsed a week after a group of “expert” building inspectors said that it was in fine structural condition and would last another 100 years). The tower was never rebuilt.
When King Ottokar I founded the royal city of Znojmo, the castle became a city citadel and was connected to the city walls. A strong garrison was placed inside and commanded by the Royal Burgrave.
Sigismund of Luxemburg, the last Holy Roman Emperor of the House of Luxembourg died in Znojmo Castle on 9 December 1437. It is said that he fell from his horse on the Lower Square in Znojmo and was brought to the Castle where he passed away. His body was placed on show in St. Nicholas’s Church
At the end of the 17th Century when the Turkish threat was once and for all averted by Prince Eugene of Savoy the importance of Znojmo Castle diminished.
In 1710 the Roman Emperor Joseph I decided to dispose of the castle. The front castle was bought by Znojmo burghers, who used the space to build a brewery, and the rear castle became the possession of the Lords of Deblin.
In 1710-1721 the new owners had a High-Baroque Chateau built, probably designed by the well-known Austrian architect J. B. Fischer von Erlach.
The derelict old castle was demolished and the new Chateau occupied the space of the old northern and eastern wings. In the place of the castle’s former southern and western wings, a spacious cour d’honneur was created, which was not oriented towards the city (as would have been usual), but towards the beautiful deep river canyon. The oval entrance hall of the chateau (the Ancestors’ Hall) has an interesting fresco, painted by J. M. Fiseé (born in the Austrian Netherlands – now Belgium), depicting the union of the Czech lands Bohemia, Moravia and Silesia.
The Chateau lost much of its charm at the end of the 18th century and in the 19th century when it was converted into a military hospital.
Today Deblin Chateau is maintained by the South Moravian Museum and houses a permanent historical exhibition.